Annealing furnace



July 15, 1941. c. wobDsoN 2,249,411

ANNEALING FURNACE Filed Oct. 5, 1-940 2 sheets-sheet 2 INVENTOR James ClW odsn detailed description of Patented July "1 5, 1941 i James C. Woodson, Cleveland, Ohio, assignor to i Lee Wilson Sales Corporation, Cleveland. Ohio, a corporation of Ohio I Application October 5, 1940, Serial No. 359,888

4 Claims. (Cl. 2665) This invention relates to a furnace and, in particular, to a furnace of the hood or cover type particularly adapted for the annealing of sheet metaLe. g., cold-rolled ferrous strip in coils.

Cover-type annealing furnaces have been used extensively and have exhibited satisfactory operating characteristics and a high efficiency. It is an object of this invention to improve generally on cover-type furnaces as known heretofore. As generally constructed, cover-type furnaces comprise a base or hearth and a cover proper. or hood,

, removably disposed thereon. The hood is provided interiorly with heat-exchange tubes whereby a charge of material on the base is brought up, to the desired temperature. A metal protective cover is disposed over the charge before the heating cover is lowered on to the base.

I have invented a novel cover-type annealing furnace having numerous advantages over the conventional construction briefly described above In a preferred embodiment, my furnace comprises a base having a charge support thereon, a refractory base ring removably disposable on the base and having a metal protective cover permanently united therewith. Heat-exchange tubes extend through the base ring and upwardly within the protective cover. A thermal insulating tions 2| 'and 22 of substantially cylindrical shape connected by a conical portion 23. 'The upper cylindrical portion 2| is provided with a top or cover is re'movably' disposable over the protective cover and is supported on the base ring. By this construction, the heat-exchange tubes-are disposed-close .to the charge for direct radiationlofheat thereto. This shortens the time which has been necessary heretofore to bring'the charge up to the desired temperature.

other novel features and advantages'of my invention will be pointed ment which is illustrated in the accompanying drawings. In the-drawings,

Fig. 1 is a vertical, central section through a furnace according to the invention; and

out during the following the ,preferred embodi'-- Figj2 is a view partly in section and partly in plan taken along the plane of line II- -II of Fig. -1.

Referring now in detail to thedrawings, the base or hearth of the furnace is indicated generallyat l0 and comprises a pier ii of refractory brick laid up on a fabricated supporting frame |2 composed; of welded plate. The frame |2 includes a peripheral'sealing' channel l3 and a central well ll.

A charge support I! is disposed onthe pier ii I and is provided with an. annular base plate It. The support 5may conveniently be a casting and is provided with a central opening or eye I! and radial passages IS. The base plate It is adapted to receive a charge of material to be annealed. e. g.;a coil of strip l3.

A metallic protective cover 20 is fabricated of welded plate and comprises upper and lower porsheathing enclosing the lower portion 22. A sealing channel 4| extends around the lower portion of the cover 20, being disposed adjacent the air duct 31 and supported on web plates 42 extending roof 24. The lower cylindrical portion 22 is provided with-an annular flange plate 25 which car- .ries a refractory hiring or base ring 26 extending therearound andupwardly therefrom beyond the joint between the portions 22 and'23. The portion 22 has a depending flange 21 adapted to enter the sealing channel l3 in the frame of the base or hearth i0. Eyes 28 extend outwardly from the lower portion 22 for cooperation with vertical guides 29 extending upwardly from the base It. I

Heat-exchange tubes 30 are spaced circumferentially around the interior of the cover 20. The tubes are generally of U-shape having spaced legs curving outwardly adjacent their lower ends as at 3| and 32. The upper ends of the tubes are suspended from the interior of the cover'by links 33 cooperating with lugs attached to the tubes and the cover. The ends 3| of the tubes extend outwardly through openings in the base ring or lower portion of the protective cover 23 while the ends 32 penetrate the conical portion 23 of the cover.

Burner nozzles 34 are mounted in the lower ends 3| of the tubes 30. A fuel manifold 35 extends around the base ring; being supported on suitable brackets, and supplies fuel to the burner nozzles through suitable connections including individual control valves 38. An air duct 31 also extends around the base ring and connections 38 extend therefrom to the end 3| of each tube 30. Connections 39 and extend fromthe manifold 35 and duct 31 to suitable sources of fuel and air, respectively. Above the air duct 31 is a cooling ring 31a through which water is circulated by suitable connections. The cooling-ring prevents theheatto which the upper portion 2| and conical portion 23 of the cover 20 are subjected from flowing downwardly to the exposed upwardly from the flange plate 25.

A thermal insulating cover 43 is adapted to be removably disposed on the cover 23 and comprises a refractory'lining ll assembled within an enclosure of welded sheathing plates 15. An annular fiang'e plate 45 extends around the bottom of the cover 331 A depending flange 41 secured to the plate 46 has bearing pads 43 secured thereto adapted to rest on the bottom of the channel 4|, thereby supporting the cover 43 on the cover 20.

Eyes 49 extend outwardly from the plate 46 for cooperation with the guides 23. I

Spark-gap igniters 50 extend through the wall of the cover 43 adjacent the ends 32 of the tubes gas under suitable pressure.

Y cating device.

combustion gases are discharged to the atmosphere.

a and are energized b, transformers, carried an -suitable mounting bra'ckets 52. Bight open- I It will be apparent from the foregoing description that the invention is characterized by numerous advantagesover cover-typefumaces as '43. The top or roof ,of the cover 43 is provided It is desirable to a non-oxidizing at:

mosphere within the cover 23 throughout the annealing process. For this purpose, an inlet pipe It extends through the base I. and is adapt ed to be connected to a source'of. non-oxidizing Outletpipes It also extend through the base-to permitan initial purging of 'theair trapped within the cover 20 and a continuous circulation .of the non-oxidizing atmosphere, if desired: In order to permit the pressure of the atmosphere within the cover 23 to-be observed, a tubell extends through the base and(is connected to a suitable pressure-indithe lower. portion of the cover 33 and are conrespectively.

1 motor" mounted in the well u 61- the base II has a shaft extending upwardly through a sleeve I. penetrating .the pier II. A fan ii is mounted on the shaft of the motor within the heretofore constructed. In the first place, the

location of the" heat-exchange tubes within the protectivecover greatly expedites the heating of. the charge because the tubes are close to the charge and radiate directly thereto without any intermediate obstruction; Good thermal elliciehcy is obtained by reason of the long distance traveled by the combustion gases through both 7 branches of the U-shaped'heat-exchang'e tubes.

Since the upper portion 2] of the protective cover '23 is permanently united with the lower.

' portion 22 thereof, it is'unnecessary to provide any seal for a joint within the cover 43. Since both the sealing channels l3(and4l are on the exterior of the fumace, a liquid sealing medium may be-employed. This provides better sealing Manometers' 53- are mounted on 'nected to the fuel manifold 35 and air duct 31,

than the sand seal which has been necessary heretofore inside the furnace cover.

Although I have illustrated and described but a preferred embodiment of. the invention, it will be recognized that changes in the construction and arrangement of parts may be made without departing from the spirit of the invention or v the scope of the appended claims. The base and covers, for example, could be made rectangular eye or central opening ll of the casting l5. This fan, when driven; circulates the atmosphere with- .base plate It; The covers and 43 are then -.in the cover 23 upwardly around the coil l3 and" downwardly through the center .thereof or vicev versa.

lowered successively over the coil. After the air I trapped within the cover "has been purged and the desired atmosphere established therein, fuel and air are admitted to the manifold 35 and the duct 31. The igniters 33 are then energized and ignite the'combuatible mixture issuing from the n ends 32 of the tubes 33. After ignition, of course, combustion commences close to the ends of the nozzles 34 andcontiniiesthroughout a substantial portion of the entire length of the tubes 3|.

These tubes thus become heated to radiant tem'- perature and radiate heat directly to the coil l3. Absorption of heat by the coil. is also facilitated by the circulation of the atmosphere within the cover II which iseflected by the fan 6|. vCombustion gases issuing from the ends 32 of thetube's 3. flow upwardlyfpast the upper portion 2| of the cover if and out through the exhaust port "in thecover 43.

When the coil I! has been brought up to the proper'temperature, the supply. of fuel and' air to the manifold 35 and duct 31, respectively; is discontinued and the cover 43 is lifted to permit atmospheric cooling of the coil IS. The cover 2| remains in position during the cooling stage. When thecoil has been cooled to a temperature below that at which atmospheric oxidation proceeds rapidly, thecover Ill is raised, the cell I) removed and replaced by another coil to be annealed, whereupon the'cover 20 is again placed over the coil and the cover "lowered into position. It will be understood that a cover such as that indicated at 2| is provided for each base I. in a multiple unit installation. A single.

cover such as that shown at 43 can be used successively in conjunction with different bases and heating covers. 7

instead of circular, for the purpose of annealing arable upper and lower portions, a protective metal cover permanently united with'said lower portion and extending inwardly of and upwardly within said upper portion, and heat-exchange tubes mounted inside said p tective cover,'one end of each tube penetrating he lower portion of said side walls, the other'end of each tube penetrating the protective cover above the lower portion of said side walls.

2. In an annealing furnace, a base having a charge support thereon, a rerracto yyau removably disposed on said base, a protective inetal cover including a topand side walls permanently united with said wall, heat-exchange tubes within said cover, one end of stantially the same diameter as said insulating.

cover. 4. In an charge supp rt thereon, a base ring of refractory material removablydisposed on said base, a metal A protective cover having-a top and side walls permanently united to said ring, U-shaped heatexchang'e' tubes extending upwardly along the side wallsof said cover, one branch. of each tube penetrating said ring and the other the side wall or the covenand an insulating cover, removably disposed over said protective cover.

JAMES c. WooDsoN.

each tube penetrating the wall and the other end the-side, wall of the annealing furnace, a base having a r 

